Previously, in Chats when the list of text boxes was scrolled to the bottom, any additional messages, either typed by user or received from other users, was added to the bottom and the list was scrolled up to reveal it. After upgrading to Catalina yesterday, this autoscrolling behavior has stopped working. When user types a message and hits return, the new message is hidden. Likewise, messages from other users are not revealed by scrolling up. So one has to constantly manually scroll up to see the message thread.

Adium is developed in the ​Objective-C language using ​Apple's Cocoa frameworks and licensed under the ​GNU GPL open source license. The libpurple protocol library which provides connectivity on many instant messaging services is written in C and maintained mostly by the developers of ​Pidgin. - https://trac.adium.im/wiki/Development